The other day my wife asked me, "Is it 2008? Or 2009? I forget." This would probably be difficult to do outside of Japan, but here it's possible here due to the Japanese calendar system, which marks years by the current Emperor. The current year is Heisei 21, the 21st year of the reign of Emperor Akihito -- although don't expect any Japanese to know that name, as he's always called "Emperor Heisei" in Japanese -- and any kind of official document will always refer to this year as Heisei 21 rather than 2009. Having two systems to remember important dates in can be a challenge -- for example, I came to Japan in Heisei 3 (1991), my kids were born in Heisei 7 and 8 (1995 and 1996), and my car's sha-ken (a maintenance check-up you have to get every 2 years) is due in March of Heisei 23 (2011).
Former PM stud-muffin Obuchi was the one to announce the Heisei era name.